package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
//          互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);
//        解决缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(RedisConstants.CACHE_SHOP_KEY,id,Shop.class,this::getById,RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES);
//        过期时间解决缓存击穿
//        Shop shop = cacheClient.queryWithLogicalExpire(RedisConstants.CACHE_SHOP_KEY,RedisConstants.LOCK_SHOP_KEY,id,Shop.class,this::getById,10L,TimeUnit.SECONDS);
        if(shop==null){
            return Result.fail("店铺信息不存在！");
        }
        return Result.ok(shop);

    }
    public Shop queryWithMutex(Long id){
        //        1.从redis中查缓存
        String key = RedisConstants.CACHE_SHOP_KEY +id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        Shop shop;
//        2.若存在于缓存
        if(StrUtil.isNotBlank(shopJson)) {

            shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        //        判断是否命中的是空值"" 不为null一定是""
        if(shopJson!=null){
            return null;
        }
//        3.若不存在于缓存 实现缓存重建
        String lockKey = "lock:shop:"+id;
        try {
            boolean isLock = tryLock(lockKey);
//        3.1获取互斥锁 判断是否获取成功
            if(!isLock){
//            3.2失败 休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
//
            shop = getById(id);
//            模拟重建的延时
            Thread.sleep(200);
            if(shop == null){
//            将空值写入redis 防止缓存穿透
                stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;

            }
//        4.存在数据库 返回 写redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);

        }catch (InterruptedException e){
            throw new RuntimeException(e);
        }finally {
            unlock(lockKey);
        }
         return shop;
    }


    /**
     * 互斥锁上锁
     * @param key
     * @return
     */
    private boolean tryLock(String key){
//        若键值对已存在 返回false
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10,TimeUnit.SECONDS);
//        直接返回flag会拆箱 可能会返回空值
        return BooleanUtil.isTrue(flag);
    }

    /**
     * 互斥锁解锁
     * @param key
     */
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    /**
     * 店铺信息加上逻辑过期时间写入redis
     * @param id
     * @param expireSeconds
     */
    public void saveShop2Redis(Long id,Long expireSeconds){
//        查询店铺数据
        Shop shop = getById(id);
//        封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
//        写入redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
    @Transactional
    @Override
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
//        1.更新数据库
        updateById(shop);
//        2.删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if(x==null||y==null){
            //不需要坐标查询 直接数据库查
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current*SystemConstants.DEFAULT_PAGE_SIZE;
        // 3.查询redis 按照距离排序 分页
        String key = RedisConstants.SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        if(list.size()<from){
            //没有下一页
            return Result.ok(Collections.emptyList());
        }
        //因为redis geo只能从头查 不能从某一个位置查 需要对结果进行截取
        list.stream().skip(from).forEach(result ->{
            //获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        // 4.解析出id并查询出店铺
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
